$-qr + 9r + 9s - 6 = 3r - 7s - 5$ Solve for $q$.
Solution: Combine constant terms on the right. $-qr + 9r + 9s - {6} = 3r - 7s - {5}$ $-qr + 9r + 9s = 3r - 7s + {1}$ Combine $s$ terms on the right. $-qr + 9r + {9s} = 3r - {7s} + 1$ $-qr + 9r = 3r - {16s} + 1$ Combine $r$ terms on the right. $-qr + {9r} = {3r} - 16s + 1$ $-qr = -{6r} - 16s + 1$ Isolate $q$ $-q{r} = -6r - 16s + 1$ $q = \dfrac{ -6r - 16s + 1 }{ -{r} }$ Swap the signs so the denominator isn't negative. $q = \dfrac{ {6}r + {16}s - {1} }{ {r} }$